Techniques relating to data preservation have been known. For example, a system, which acquires a digest of data and checks whether the data matches data held in a terminal, has been known. In addition, a system, which erases a file from a storage device when an erase keyword coinciding with a keyword assigned to a file is input, has been known.
Conventionally, however, there is a case where erroneous erasing or erroneous updating of data is performed due to vulnerability of a program operating on a host processor. Thus, conventionally, it is sometimes difficult to preserve data of the storage device.